Advanced Computer Graphics - Students corner....



IndexContents1. IntroductionDefinitionMeaningHistorical ProspectiveObjective, scope and limitations2. LiteratureWhatHow3. Research DesignHypothesis4. ResearchHowInput and Output5. Data Analysis6. SynthesisIntroductionGeneral Observation & Specification7. ConclusionFinding Implementation TOC \o "1-3" \h \z \u Initial Development of Computer Graphics PAGEREF _Toc287878772 \h 2Image types PAGEREF _Toc287878773 \h 52D computer graphics PAGEREF _Toc287878774 \h 53D computer graphics PAGEREF _Toc287878775 \h 6Computer animation PAGEREF _Toc287878776 \h 7Concepts and principles PAGEREF _Toc287878777 \h 7Rendering PAGEREF _Toc287878778 \h 8Volume rendering PAGEREF _Toc287878779 \h 103D modelling PAGEREF _Toc287878780 \h 10Subfields in computer graphics PAGEREF _Toc287878781 \h 12Geometry PAGEREF _Toc287878782 \h 13Animation PAGEREF _Toc287878783 \h 14Rendering PAGEREF _Toc287878784 \h 14Geometry processing PAGEREF _Toc287878785 \h 15Cloth modelling PAGEREF _Toc287878786 \h 15Deformable solids PAGEREF _Toc287878788 \h 17Mass-spring models PAGEREF _Toc287878789 \h 18Finite element simulation PAGEREF _Toc287878790 \h 18Energy minimization methods PAGEREF _Toc287878791 \h 19Shape matching PAGEREF _Toc287878792 \h 19Rigid-body based deformation PAGEREF _Toc287878793 \h 19Force-based cloth PAGEREF _Toc287878794 \h 20Position-based dynamics PAGEREF _Toc287878795 \h 20Collision detection for deformable objects PAGEREF _Toc287878796 \h 21Rigid body dynamics PAGEREF _Toc287878797 \h 22Rigid body linear momentum PAGEREF _Toc287878798 \h 23Rigid body angular momentum PAGEREF _Toc287878799 \h 24Angular momentum and torque PAGEREF _Toc287878800 \h 24Applications PAGEREF _Toc287878801 \h 25AutoCAD origin PAGEREF _Toc287878802 \h 26AutoCAD LT PAGEREF _Toc287878803 \h 27AutoCAD Freestyle PAGEREF _Toc287878804 \h 27Student versions PAGEREF _Toc287878805 \h 27Vertical programs PAGEREF _Toc287878806 \h 28AutoCAD Architecture PAGEREF _Toc287878807 \h 28Autodesk Maya PAGEREF _Toc287878808 \h 29Awards PAGEREF _Toc287878809 \h 30Overview PAGEREF _Toc287878810 \h 30Maya Embedded Language PAGEREF _Toc287878811 \h 31System requirements PAGEREF _Toc287878812 \h 32Operating systems PAGEREF _Toc287878813 \h 32Autodesk Revit PAGEREF _Toc287878814 \h 32Modelling PAGEREF _Toc287878815 \h 33Intended use PAGEREF _Toc287878816 \h 34Family based content PAGEREF _Toc287878817 \h 34Rendering PAGEREF _Toc287878818 \h 34Autodesk 3ds Max PAGEREF _Toc287878819 \h 35Modelling techniques PAGEREF _Toc287878820 \h 39Polygon modelling PAGEREF _Toc287878821 \h 39NURBS or non-uniform rational B-spline PAGEREF _Toc287878822 \h 39Surface tool/Editable patch object PAGEREF _Toc287878823 \h 40Predefined primitives PAGEREF _Toc287878824 \h 40Predefined Standard Primitives list PAGEREF _Toc287878825 \h 41Predefined Extended Primitives list PAGEREF _Toc287878826 \h 41Rendering PAGEREF _Toc287878827 \h 42DefinitionThe development of computer graphics?has made computers easier to interact with, and better for understanding and interpreting many types of data. Developments in computer graphics have had a profound impact on many types of media and have revolutionized?animation,?movies?and the?video game industry. The term computer graphics has been used in a broad sense to describe "almost everything on computers that is not text or sound". Typically, the term?computer graphics?refers to several different things:the?representation?and?manipulation?of?image?data?by a?computerthe various?technologies?used to create and manipulate imagesthe?images?so produced, andthe sub-field of?computer science?which studies methods for digitally synthesizing and manipulating visual content, see?study of computer graphicsMeaningToday, computers and computer-generated images touch many aspects of daily life. Computer imagery is found on television, in newspapers, for example in weather reports, or for example in all kinds of medical investigation and surgical procedures. A well-constructed?graph?can present complex statistics in a form that is easier to understand and interpret. In the media "such graphs are used to illustrate papers, reports, thesis", and other presentation material.Many powerful tools have been developed to visualize data. Computer generated imagery can be categorized into several different types: 2D, 3D, 4D, 7D, and animated graphics. As technology has improved, 3D computer graphics have become more common, but 2D computer graphics are still widely used. Computer graphics has emerged as a sub-field of?computer science?which studies methods for digitally synthesizing and manipulating visual content. Over the past decade, other specialized fields have been developed like?information visualization, and?scientific visualization?more concerned with "the visualization of?three dimensional?phenomena (architectural, meteorological, medical,?biological, etc.), where the emphasis is on realistic renderings of volumes, surfaces, illumination sources, and so forth, perhaps with a dynamic (time) component".Historical ProspectiveThe advance in computer graphics was to come from Ivan Sutherland. In 1961 Sutherland created another computer drawing program called Sketchpad. Using a light pen, Sketchpad allowed one to draw simple shapes on the computer screen, save them and even recall them later. The light pen itself had a small photoelectric cell in its tip. This cell emitted an electronic pulse whenever it was placed in front of a computer screen and the screen's electron gun fired directly at it. By simply timing the electronic pulse with the current location of the electron gun, it was easy to pinpoint exactly where the pen was on the screen at any given moment. Once that was determined, the computer could then draw a cursor at that location.Sutherland seemed to find the perfect solution for many of the graphics problems he faced. Even today, many standards of computer graphics interfaces got their start with this early Sketchpad program. One example of this is in drawing constraints. If one wants to draw a square for example, s/he doesn't have to worry about drawing four lines perfectly to form the edges of the box. One can simply specify that s/he wants to draw a box, and then specify the location and size of the box. The software will then construct a perfect box, with the right dimensions and at the right location. Another example is that Sutherland's software modeled objects - not just a picture of objects. In other words, with a model of a car, one could change the size of the tires without affecting the rest of the car. It could stretch the body of the car without deforming the tires.These early computer graphics were Vector graphics, composed of thin lines whereas modern day graphics are Raster based using pixels. The difference between vector graphics and raster graphics can be illustrated with a shipwrecked sailor. He creates an SOS sign in the sand by arranging rocks in the shape of the letters "SOS." He also has some brightly colored rope, with which he makes a second "SOS" sign by arranging the rope in the shapes of the letters. The rock SOS sign is similar to raster graphics. Every pixel has to be individually accounted for. The rope SOS sign is equivalent to vector graphics. The computers simply sets the starting point and ending point for the line and perhaps bend it a little between the two end points. The disadvantages to vector files are that they cannot represent continuous tone images and they are limited in the number of colors available. Raster formats on the other hand work well for continuous tone images and can reproduce as many colors as needed.Also in 1961 another student at MIT, Steve Russell, created the first video game, Spacewar. Written for the DEC PDP-1, Spacewar was an instant success and copies started flowing to other PDP-1 owners and eventually even DEC got a copy. The engineers at DEC used it as a diagnostic program on every new PDP-1 before shipping it. The sales force picked up on this quickly enough and when installing new units, would run the world's first video game for their new customers.E. E. Zajac, a scientist at Bell Telephone Laboratory (BTL), created a film called "Simulation of a two-giro gravity attitude control system" in 1963. In this computer generated film, Zajac showed how the attitude of a satellite could be altered as it orbits the Earth. He created the animation on an IBM 7090 mainframe computer. Also at BTL, Ken Knowlton, Frank Sindon and Michael Noll started working in the computer graphics field. Sindon created a film called Force, Mass and Motion illustrating Newton's laws of motion in operation. Around the same time, other scientists were creating computer graphics to illustrate their research. At Lawrence Radiation Laboratory, Nelson Max created the films, "Flow of a Viscous Fluid" and "Propagation of Shock Waves in a Solid Form." Boeing Aircraft created a film called "Vibration of an Aircraft."It wasn't long before major corporations started taking an interest in computer graphics. TRW, Lockheed-Georgia, General Electric and Sperry Rand are among the many companies that were getting started in computer graphics by the mid 1960's. IBM was quick to respond to this interest by releasing the IBM 2250 graphics terminal, the first commercially available graphics computer.Ralph Baer, a supervising engineer at Sanders Associates, came up with a home video game in 1966 that was later licensed to Magnavox and called the Odyssey. While very simplistic, and requiring fairly inexpensive electronic parts, it allowed the player to move points of light around on a screen. It was the first consumer computer graphics product.Also in 1966, Sutherland at MIT invented the first computer controlled head-mounted display (HMD). Called the Sword of Damocles because of the hardware required for support, it displayed two separate wireframe images, one for each eye. This allowed the viewer to see the computer scene in stereoscopic 3D. After receiving his Ph.D. from MIT, Sutherland became Director of Information Processing at ARPA (Advanced Research Projects Agency), and later became a professor at Harvard.Dave Evans was director of engineering at Bendix Corporation's computer division from 1953 to 1962, after which he worked for the next five years as a visiting professor at Berkeley. There he continued his interest in computers and how they interfaced with people. In 1968 the University of Utah recruited Evans to form a computer science program, and computer graphics quickly became his primary interest. This new department would become the world's primary research center for computer graphics.In 1967 Sutherland was recruited by Evans to join the computer science program at the University of Utah. There he perfected his HMD. Twenty years later, NASA would re-discover his techniques in their virtual reality research. At Utah, Sutherland and Evans were highly sought after consultants by large companies but they were frustrated at the lack of graphics hardware available at the time so they started formulating a plan to start their own company.A student by the name of?Edwin Catmull?started at the University of Utah in 1970 and signed up for Sutherland's computer graphics class. Catmull had just come from The Boeing Company and had been working on his degree in physics. Growing up on Disney, Catmull loved animation yet quickly discovered that he didn't have the talent for drawing. Now Catmull (along with many others) saw computers as the natural progression of animation and they wanted to be part of the revolution. The first animation that Catmull saw was his own. He created an animation of his hand opening and closing. It became one of his goals to produce a feature length motion picture using computer graphics. In the same class, Fred Parke created an animation of his wife's face. Because of Evan's and Sutherland's presence, UU was gaining quite a reputation as the place to be for computer graphics research so Catmull went there to learn 3D animation.As the UU computer graphics laboratory was attracting people from all over,?John Warnock?was one of those early pioneers; he would later found Adobe Systems and create a revolution in the publishing world with his PostScript page description language. Tom Stockham led the image processing group at UU which worked closely with the computer graphics lab. Jim Clark was also there; he would later found Silicon Graphics, Inc.The first major advance in 3D computer graphics was created at UU by these early pioneers, the hidden-surface algorithm. In order to draw a representation of a 3D object on the screen, the computer must determine which surfaces are "behind" the object from the viewer's perspective, and thus should be "hidden" when the computer creates (or renders) the image.Literature2D computer graphics2D computer graphics?are the computer-based generation of?digital images—mostly from two-dimensional models, such as?2D geometric models, text, and digital images, and by techniques specific to them.2D computer graphics are mainly used in applications that were originally developed upon traditional?printing?and?drawing?technologies, such as?typography, cartography,?technical drawing,?advertising, etc.. In those applications, the two-dimensional?image?is not just a representation of a real-world object, but an independent artifact with added semantic value; two-dimensional models are therefore preferred, because they give more direct control of the image than?3D computer graphics, whose approach is more akin to?photography?than to?typography.Pixel artPixel art?is a form of?digital art, created through the use of?raster graphics?software, where images are edited on the?pixel?level. Graphics in most old (or relatively limited) computer and video games,?graphing calculator?games, and many?mobile phone?games are mostly pixel art.Vector graphicsVector graphics?formats are complementary to?raster graphics, which is the representation of images as an array of?pixels, as it is typically used for the representation of photographic images?[4]?Vector graphics consists in encoding information about shapes and colors that comprise the image, which can allow for more flexibility in rendering. There are instances when working with vector tools and formats is best practice, and instances when working with raster tools and formats is best practice. There are times when both formats come together. An understanding of the advantages and limitations of each technology and the relationship between them is most likely to result in efficient and effective use of tools.3D computer graphics3D computer graphics?in contrast to?2D computer graphics?are graphics that use a?three-dimensional?representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. Such images may be for later display or for real-time viewing.Despite these differences, 3D computer graphics rely on many of the same?algorithms?as 2D computer?vector graphics?in the?wire frame modeland 2D computer?raster graphics?in the final rendered display. In computer graphics software, the distinction between 2D and 3D is occasionally blurred; 2D applications may use 3D techniques to achieve effects such as lighting, and primarily 3D may use 2D rendering techniques.3D computer graphics are often referred to as?3D models. Apart from the rendered graphic, the model is contained within the graphical data file. However, there are differences. A 3D model is the?mathematical?representation of any?three-dimensional?object. A model is not technically a graphic until it is visually displayed. Due to?3D printing, 3D models are not confined to virtual space. A model can be displayed visually as a two-dimensional image through a process called?3D rendering,?or used in non-graphical?computer simulations?and calculations. There are some?3D computer graphics software?for users to create 3D puter animationComputer animation?is the art of creating moving images via the use of?computers. It is a subfield of computer graphics and?animation. Increasingly it is created by means of?3D computer graphics, though?2D computer graphics?are still widely used for stylistic, low bandwidth, and faster real-time rendering needs. Sometimes the target of the animation is the computer itself, but sometimes the target is another medium, such as?film. It is also referred to as CGI (Computer-generated imagery?or computer-generated imaging), especially when used in films.Virtual entities may contain and be controlled by assorted attributes, such as transform values (location, orientation, and scale) stored in an object's?transformation matrix. Animation is the change of an attribute over time. Multiple methods of achieving animation exist; the rudimentary form is based on the creation and editing of?key frames, each storing a value at a given time, per attribute to be animated. The 2D/3D graphics software will?interpolate?between key frames, creating an editable curve of a value mapped over time, resulting in animation. Other methods of animation include?procedural?and?expression-based techniques: the former consolidates related elements of animated entities into sets of attributes, useful for creating?particle?effects and?crowd simulations; the latter allows an evaluated result returned from a user-defined logical expression, coupled with mathematics, to automate animation in a predictable way (convenient for controlling bone behaviour beyond what a?hierarchy?offers in?skeletal system?set up).To create the illusion of movement, an image is displayed on the computer?screen?then quickly replaced by a new image that is similar to the previous image, but shifted slightly. This technique is identical to the illusion of movement in?television?and?motion pictures.ResearchImages are typically produced by? optical? devices; such as? cameras,? mirrors,?lenses,?telescopes,?microscopes, etc. and natural objects and phenomena, such as the?human eye?or water surfaces.A?digital image?is a representation of a two-dimensional?image?in binary format as a sequence of ones and zeros. Digital images include both?vector?images and?raster?images, but raster images are more commonly used. In digital imaging, a?pixel?(or picture element) is a single point in a?raster image. Pixels are normally arranged in a regular 2-dimensional grid, and are often represented using dots or squares. Each pixel is a?sample?of an original image, where more samples typically provide a more accurate representation of the original. The?intensity?of each pixel is variable; in color systems, each pixel has typically three components such as?red, green, and blue.GraphicsGraphics?are?visual?presentations on some surface, such as a wall,?canvas, computer screen, paper, or stone to?brand, inform, illustrate, or entertain. Examples are?photographs,?drawings,?line art,?graphs,?diagrams,?typography,?numbers,?symbols,?geometric?designs,?maps,engineering drawings, or other?images. Graphics often combine?text,?illustration, and?color. Graphic design may consist of the deliberate selection, creation, or arrangement of typography alone, as in a brochure, flier, poster, web site, or book without any other element. Clarity or effective communication may be the objective, association with other cultural elements may be sought, or merely, the creation of a distinctive style.RenderingRendering is the process of generating an image from a?model?(or models in what collectively could be called a?scene?file), by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint,?texture,lighting, and?shading?information as a description of the virtual scene. The data contained in the scene file is then passed to a rendering program to be processed and output to a?digital image?or?raster graphics?image file. The rendering program is usually built into the computer graphics software, though others are available as plug-ins or entirely separate programs. The term "rendering" may be by analogy with an "artist's rendering" of a scene. Though the technical details of rendering methods vary, the general challenges to overcome in producing a 2D image from a 3D representation stored in a scene file are outlined as the?graphics pipeline?along a rendering device, such as a?GPU. A GPU is a purpose-built device able to assist a?CPU?in performing complex rendering calculations. If a scene is to look relatively realistic and predictable under virtual lighting, the rendering software should solve the?rendering equation. The rendering equation doesn't account for all lighting phenomena, but is a general lighting model for computer-generated imagery. 'Rendering' is also used to describe the process of calculating effects in a video editing file to produce final video output.3D projection3D projection?is a method of mapping three dimensional points to a two dimensional plane. As most current methods for displaying graphical data are based on planar two dimensional media, the use of this type of projection is widespread, especially in computer graphics, engineering and drafting.Ray tracingRay tracing?is a technique for generating an?image?by tracing the path of?light?through?pixels?in an?image plane. The technique is capable of producing a very high degree ofphotorealism; usually higher than that of typical?scanline rendering?methods, but at a greater?computational cost.ShadingShading?refers to?depicting?depth in?3D models?or illustrations by varying levels of?darkness. It is a process used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter shade for lighter areas. There are various techniques of shading including?cross hatching?where perpendicular lines of varying closeness are drawn in a grid pattern to shade an area. The closer the lines are together, the darker the area appears. Likewise, the farther apart the lines are, the lighter the area appears. The term has been recently generalized to mean that?shaders?are applied.Texture mappingTexture mapping?is a method for adding detail, surface texture, or colour to a?computer-generated graphic?or?3D model. Its application to 3D graphics was pioneered by Dr?Edwin Catmull?in 1974. A texture map is applied (mapped) to the surface of a shape, or polygon. This process is akin to applying patterned paper to a plain white box. Multitexturing is the use of more than one texture at a time on a polygon.[6]?Procedural textures?(created from adjusting parameters of an underlying algorithm that produces an output texture), and?bitmap textures?(created in an?image editing?application) are, generally speaking, common methods of implementing texture definition from a 3D animation program, while intended placement of textures onto a model's surface often requires a technique known as?UV mapping.Anti-aliasingRendering resolution-independent entities (such as 3D models) for viewing on a raster (pixel-based) device such as a?LCD display?or?CRT television?inevitably causes?aliasing artifactsmostly along geometric edges and the boundaries of texture details; these artifacts are informally called "jaggies". Anti-aliasing methods rectify such problems, resulting in imagery more pleasing to the viewer, but can be somewhat computationally expensive. Various anti-aliasing algorithms (such as?supersampling) are able to be employed, then customized for the most efficient rendering performance versus quality of the resultant imagery; a graphics artist should consider this trade-off if anti-aliasing methods are to be used. A pre-anti-aliased?bitmap texture?being displayed on a screen (or screen location) at a resolution different than the resolution of the texture itself (such as a textured model in the distance from the virtual camera) will exhibit aliasing artifacts, while any?procedurally-defined texture?will always show aliasing artifacts as they are resolution-independent; techniques such asmipmapping?and?texture filtering?help to solve texture-related aliasing problems.Volume renderingVolume rendering?is a technique used to display a?2D projection?of a 3D discretely?sampled?data set. A typical 3D data set is a group of 2D slice images acquired by a?CT?or?MRI?scanner.Usually these are acquired in a regular pattern (e.g., one slice every millimetre) and usually have a regular number of image?pixels?in a regular pattern. This is an example of a regular volumetric grid, with each volume element, or?voxel?represented by a single value that is obtained by sampling the immediate area surrounding the voxel.3D modelling3D modelling?is the process of developing a mathematical,?wireframe?representation of any three-dimensional object, called a "3D model", via specialized software. Models may be created automatically or manually; the manual modelling process of preparing geometric data for 3D computer graphics is similar to?plastic arts?such as?sculpting. 3D models may be created using multiple approaches: use of?NURBS?curves to generate accurate and smooth surface patches,?polygonal mesh modelling?(manipulation of faceted geometry), or polygonal mesh?subdivision(advanced tessellation of polygons, resulting in smooth surfaces similar to NURBS models). A 3D model can be displayed as a two-dimensional image through a process called?3D rendering.Pioneers in graphic designCharles CsuriCharles Csuri?is a pioneer in computer animation and digital fine art and created the first computer art in 1964. Csuri was recognized by?Smithsonian?as the father of digital art and computer animation, and as a pioneer of computer animation by the?Museum of Modern Art?(MoMA) and?Association for Computing Machinery-SIGGRAPH.Donald P. GreenbergDonald P. Greenberg?is a leading innovator in computer graphics. Greenberg has authored hundreds of articles and served as a teacher and mentor to many prominent computer graphic artists, animators, and researchers such as?Robert L. Cook,?Marc Levoy, and?Wayne Lytle. Many of his former students have won Academy Awards for technical achievements and several have won the?SIGGRAPH?Achievement Award. Greenberg was the founding director of the NSF Center for Computer Graphics and Scientific Visualization.A. Michael NollNoll?was one of the first researchers to use a?digital?computer?to create artistic patterns and to formalize the use of random processes in the creation of?visual arts. He began creating digital computer art in 1962, making him one of the earliest digital computer artists. In 1965, Noll along with Frieder Nake and Georg Nees were the first to publicly exhibit their computer art. During April 1965, the Howard Wise Gallery exhibited Noll's computer art along with random-dot patterns by?Bela Julesz.Other pioneersJim BlinnArambiletBeno?t B. MandelbrotHenri GouraudBui Tuong PhongPierre BézierPaul de CasteljauDaniel J. SandinAlvy Ray SmithTon RoosendaalIvan SutherlandComputer graphics studies the manipulation of visual and geometric information using computational techniques. It focuses on the?mathematical?and?computational?foundations of image generation and processing rather than purely?aesthetic?issues. Computer graphics is often differentiated from the field of?visualization, although the two fields have many similarities.Connected studies include:Scientific visualizationInformation visualizationComputer visionImage processingComputational GeometryComputational TopologyApplied mathematicsApplications of computer graphics include:Special effectsVisual effectsVideo gamesDigital artSubfields in computer graphicsA broad classification of major subfields in computer graphics might be:Geometry: studies ways to represent and process surfacesAnimation: studies with ways to represent and manipulate motionRendering: studies algorithms to reproduce light transportImaging: studies image acquisition or image editingGeometryThe subfield of geometry studies the representation of three-dimensional objects in a discrete digital setting. Because the appearance of an object depends largely on its exterior,?boundary representations?are most commonly used. Two dimensional?surfaces?are a good representation for most objects, though they may be non-manifold. Since surfaces are not finite, discrete digital approximations are used.?Polygonal meshes?(and to a lesser extent?subdivision surfaces) are by far the most common representation, although point-based representations have become more popular recently (see for instance the?Symposium on Point-Based Graphics). These representations are?Lagrangian,?meaning the spatial locations of the samples are independent. Recently,?Eulerian?surface descriptions (i.e., where spatial samples are fixed) such as?level sets?have been developed into a useful representation for deforming surfaces which undergo many topological changes (with?fluids?being the most notable example).Geometry SubfieldsImplicit surface modeling - an older subfield which examines the use of algebraic surfaces,?constructive solid geometry, etc., for surface representation.Digital geometry processing -?surface reconstruction, simplification, fairing, mesh repair,?parameterization, remeshing,?mesh generation, surface compression, and surface editing all fall under this heading. Discrete differential geometry - a nascent field which defines geometric quantities for the discrete surfaces used in computer graphics. Point-based graphics - a recent field which focuses on points as the fundamental representation of surfaces.Subdivision surfacesOut-of-core mesh processing - another recent field which focuses on mesh datasets that do not fit in main memory.AnimationThe subfield of animation studies descriptions for surfaces (and other phenomena) that move or deform over time. Historically, most work in this field has focused on parametric and data-driven models, but recently?physical simulation?has become more popular as computers have become more powerful computationally.SubfieldsPerformance captureCharacter animationPhysical simulation (e.g.?cloth modelling, animation of?fluid dynamics, etc.)RenderingRendering generates images from a model. Rendering may simulate?light transport?to create realistic images or it may create images that have a particular artistic style in?non-photorealistic rendering. The two basic operations in realistic rendering are transport (how much light passes from one place to another) and scattering (how surfaces interact with light). See?Rendering (computer graphics)?for more information.TransportTransport?describes how illumination in a scene gets from one place to another.?Visibility?is a major component of light transport.ScatteringModels of?scattering?and?shading?are used to describe the appearance of a surface. In graphics these problems are often studied within the context of rendering since they can substantially affect the design of rendering algorithms. Shading can be broken down into two orthogonal issues, which are often studied independently:scattering?- how light interacts with the surface?at a given pointshading?- how material properties vary across the surfaceThe former problem refers to?scattering, i.e., the relationship between incoming and outgoing illumination at a given point. Descriptions of scattering are usually given in terms of a?bidirectional scattering distribution function?or BSDF. The latter issue addresses how different types of scattering are distributed across the surface (i.e., which scattering function applies where). Descriptions of this kind are typically expressed with a program called a?shader. (Note that there is some confusion since the word "shader" is sometimes used for programs that describe local?geometric?variation.)Other subfieldsPhysically-based rendering - concerned with generating images according to the laws of?geometric optics.Real time rendering?- focuses on rendering for interactive applications, typically using specialized hardware like?GPUs.Non-photorealistic rendering.Relighting - recent area concerned with quickly re-rendering scenes.Geometry processingGeometry processing, or mesh processing, is a fast-growing area of?research?that uses concepts from?applied mathematics,?computer science?and?engineering?to design efficient algorithms?for the acquisition, reconstruction, analysis, manipulation, simulation and transmission of complex 3D models. Applications of geometry processing algorithms already cover a wide range of areas from?multimedia,?entertainment?and classical?computer-aided design, to?biomedical computing,?reverse engineering?and?scientific computing.Cloth modellingCloth modelling?is the term used for simulating cloth within a computer program usually in the realm of?computer graphics?. The main approaches used for this may be classified into three basic types: geometric, physical, and particle/energy.Most models of cloth are based on "particles" of mass connected together in some manner of mesh.?Newtonian Physics?is used to model each particle through the use of a "black box" called a?physics engine. This involves using the basic law of motion (Newton's Second Law):In all of these models, the goal is to find the position and shape of a piece of fabric using this basic equation and several other methods.Geometric methodsWeil pioneered the first of these, the geometric technique, in 1986.[1]?His work was focused on approximating the look of cloth by treating cloth like a collection of cables and using Hyperbolic cosine?(catenary) curves. Because of this, it is not suitable for dynamic models but works very well for stationary or single-frame renders?[1]. This technique creates an underlying shape out of single points; then, it parses through each set of three of these points and maps a catenary curve to the set. It then takes the lowest out of each overlapping set and uses it for the render.Physical methodsThe second technique treats cloth like a grid work of particles connected to each other by springs. Whereas the geometric approach accounted for none of the inherent stretch of a woven material, this physical model accounts for stretch (tension), stiffness, and weight:E(Particlei,j) =?ksEs,i,j?+?kbEb,i,j?+?kgEg,i,js terms are elasticity (by?Hooke's Law)b terms are bendingg terms are gravity (see?Acceleration due to gravity)Now we apply the basic principle of?mechanical equilibrium?in which all bodies seek lowest energy by differentiating this equation to find the minimum energy.Particle/energy methodsThe last method is more complex than the first two. The particle technique takes the physical technique from (f) a step further and supposes that we have a network of particles interacting directly. That is to say, that rather than springs, we use the energy interactions of the particles to determine the cloth’s shape. For this we use an energy equation that adds on to the following:UTotal?=?URepel?+?UStretch?+?UBend?+?UTrellis?+?UGravityThe energy of repelling is an artificial element we add to prevent cloth from intersecting itself.The energy of stretching is governed by?Hooke's law?as with the Physical Method.The energy of bending describes the stiffness of the fabricThe energy of trellising describes the shearing of the fabric (distortion within the plane of the fabric)The energy of gravity is based on?acceleration due to gravityWe can also add terms for energy added by any source to this equation, then derive and find minima, which generalizes our model. This allows us to model cloth behaviour under any circumstance, and since we are treating the cloth as a collection of particles its behaviour can be described with the dynamics provided in our physics engine.DynamicsSoft body dynamicsSoft body?dynamics?is a field of?computer graphics?that focuses on visually realistic physical?simulations?of the motion and properties of?deformable?objects (or?soft bodies). The applications are mostly in video games and film. Unlike in simulation of?rigid bodies, the shape of soft bodies can change, meaning that the relative distance of two points on the object is not fixed. While the relative distances of points are not fixed, the body is expected to retain its shape to some degree (unlike a?fluid). The scope of soft body dynamics is quite broad, including simulation of soft organic materials such as muscle, fat, hair and vegetation, as well as other deformable materials such as clothing and fabric. Generally, these methods only provide visually plausible emulations rather than accurate scientific/engineering simulations, though there is some crossover with scientific methods, particularly in the case of finite element simulations. Several?physics engines?currently provide software for soft-body simulation.Deformable solidsThe simulation of volumetric solid soft bodies can be realised by using a variety of approaches.Mass-spring modelsIn this approach, the body is modeled as a set of point masses (nodes) connected by ideal weightless?elastic?springs?obeying some variant ofHooke's law. The nodes may either derive from the edges of a two-dimensional?polygonal mesh?representation of the surface of the object, or from a three-dimensional network of nodes and edges modeling the internal structure of the object (or even a one-dimensional system of links, if for example a rope or hair strand is being simulated). Additional springs between nodes can be added, or the force law of the springs modified, to achieve desired effects. Applying?Newton's second law?to the point masses including the forces applied by the springs and any external forces (due to contact, gravity, air resistance, wind, and so on) gives a system of?differential equations?for the motion of the nodes, which is solved by standard numerical schemes for solving?ODEs. Rendering of a three-dimensional mass-spring lattice is often done using free form deformation, in which the rendered mesh is embedded in the lattice and distorted to conform to the shape of the lattice as it evolves.Finite element simulationThis is a more physically accurate approach, which uses the widely used?finite element method?to solve the?partial differential equations?which govern the dynamics of an?elastic material. The body is modeled as a three-dimensional?elastic continuum?by breaking it into a large number of solid elements which fit together, and solving for the?stresses?and?strains?in each element using a model of the material. The elements are typically tetrahedral, the nodes being the vertices of the tetrahedra (relatively simple methods exist[10][11]?to?tetrahedralize?a three dimensional region bounded by a polygon mesh into?tetrahedra, similarly to how a two-dimensional?polygon?may be?triangulated?into triangles). The?strain?(which measures the local deformation of the points of the material from their rest state) is quantified by the?strain tensor?. The?stress?(which measures the local forces per-unit area in all directions acting on the material) is quantified by the?stress tensor?. Given the current local strain, the local stress can be computed via the generalized form of?Hooke's law:??where??is the "elasticity tensor" which encodes the material properties (parametrized in linear elasticity for an isotropic material by the?Poisson ratio?and?Young's modulus).The equation of motion of the element nodes is obtained by integrating the stress field over each element and relating this, via?Newton's second law, to the node accelerations.Pixelux (developers of the?Digital Molecular Matter?system) use a finite-element-based approach for their soft bodies, using a tetrahedral mesh and converting the stress tensor directly into node forces. Rendering is done via a form of?free form deformation.Energy minimization methodsThis approach is motivated by?variational principles?and the physics of surfaces, which dictate that a constrained surface will assume the shape which?minimizes the total energy of deformation?(analogous to a?soap bubble). Expressing the energy of a surface in terms of its local deformation (the energy is due to a combination of stretching and bending), the local force on the surface is given by differentiating the energy with respect to position, yielding an equation of motion which can be solved in the standard ways.Shape matchingIn this scheme, penalty forces or constraints are applied to the model to drive it towards its original shape?(i.e. the material behaves as if it has?shape memory). To conserve momentum the rotation of the body must be estimated properly, for example via?polar decomposition. To approximate finite element simulation, shape matching can be applied to three dimensional lattices and multiple shape matching constraints blended.Rigid-body based deformationDeformation can also be handled by a traditional rigid-body?physics engine, modelling the soft-body motion using a network of multiple rigid bodies connected by constraints, and using (for example)?matrix-palette skinning?to generate a surface mesh for rendering. This is the approach used for deformable objects in?Havoc.Cloth simulationIn the context of computer graphics,?cloth simulation?refers to the simulation of soft bodies in the form of two dimensional continuum elastic membranes, that is, for this purpose, the actual structure of real?cloth?on the?yarn?level can be ignored (though modelling cloth on the yarn level has been tried). Via?rendering?effects, this is capable of producing a visually plausible emulation of?textiles?and?clothing, used in a variety of contexts in video games, animation, and film. It can also be used to simulate two dimensional sheets of materials other than textiles, such as deformable metal panels or vegetation. In video games it is often used to enhance the realism of clothed characters, which otherwise would be entirely?animated.Cloth simulators are generally based on?mass-spring models, but a distinction must be made between force-based and position-based solvers.Force-based clothThe?mass-spring model?(obtained from a?polygonal mesh?representation of the cloth) determines the internal spring forces acting on the nodes at each time step (in combination with gravity and applied forces). Newton's second law gives equations of motion which can be solved via standard?ODE?solvers. To create high resolution cloth with a realistic stiffness is not possible however with simple?explicit?solvers (such as forward?Euler integration), unless the time step is made too small for interactive applications (since as is well known,?explicit integrators are numerically unstable for sufficiently?stiff?systems). Therefore?implicit solvers?must be used, requiring solution of a large?sparse matrix?system (via e.g. the?conjugate gradient method), which itself may also be difficult to achieve at interactive frame rates. An alternative?is to use an explicit method with low stiffness, with?ad hoc?methods to avoid instability and excessive stretching (e.g. strain limiting corrections).Position-based dynamicsTo avoid needing to do an expensive implicit solution of a system of?ODEs, many real-time cloth simulators (notably?PhysX,?Havok Cloth, and?Maya nCloth) use?position based dynamics(PBD), an approach based on constraint relaxation. The mass-spring model is converted into a system of constraints, which demands that the distance between the connected nodes be equal to the initial distance. This system is solved sequentially and iteratively, by directly moving nodes to satisfy each constraint, until sufficiently stiff cloth is obtained. This is similar to a?Gauss-Seidel?solution of the implicit matrix system for the mass-spring model. Care must be taken though to solve the constraints in the same sequence each timestep, to avoid spurious oscillations, and to make sure that the constraints do not violate?linear?and?angular momentum?conservation. Additional position constraints can be applied, for example to keep the nodes within desired regions of space (sufficiently close to an animated model for example), or to maintain the body's overall shape via shape matching.Collision detection for deformable objectsCollision detectionRealistic interaction of simulated soft objects with their environment may be important for obtaining visually realistic results. Cloth self-intersection is important in some applications for acceptably realistic simulated garments. This is challenging to achieve at interactive frame rates, particularly in the case of detecting and resolving self collisions and mutual collisions between two or more deformable objects.Collision detection may be?discrete/a posteriori?(meaning objects are advanced in time through a pre-determined interval, and then any penetrations detected and resolved), orcontinuous/a priori?(objects are advanced only until a collision occurs, and the collision is handled before proceeding). The former is easier to implement and faster, but leads to failure to detect collisions (or detection of spurious collisions) if objects move fast enough. Real-time systems generally have to use discrete collision detection, with other?ad hoc?ways to avoid failing to detect collisions.Detection of collisions between cloth and environmental objects with a well defined "inside" is straightforward since the system can detect unambiguously whether the cloth mesh vertices and faces are intersecting the body and resolve them accordingly. If a well defined "inside" does not exist (e.g. in the case of collision with a mesh which does not form a closed boundary), an "inside" may be constructed via extrusion. Mutual- or self-collisions of soft bodies defined by tetrahedra is straightforward, since it reduces to detection of collisions between solid tetrahedra.However, detection of collisions between two polygonal cloths (or collision of a cloth with itself) via discrete collision detection is much more difficult, since there is no unambiguous way to locally detect after a time step whether a cloth node which has penetrated is on the "wrong" side or not. Solutions involve either using the history of the cloth motion to determine if an intersection event has occurred, or doing a global analysis of the cloth state to detect and resolve self-intersections.?Pixar?has presented a method which uses a global topological analysis of mesh intersections in configuration space to detect and resolve self-interpenetration of cloth. Currently, this is generally too computationally expensive for real-time cloth systems.To do collision detection efficiently, primitives which are certainly not colliding must be identified as soon as possible and discarded from consideration to avoid wasting time. To do this, some form of?spatial subdivision?scheme is essential, to avoid a brute force test of?O[n2]?primitive collisions. Approaches used include:Bounding volume hierarchies?(AABB?trees,?OBB?trees, sphere trees)Grids, either uniform?(using?hashing?for memory efficiency) or hierarchical (e.g.?Octree,?kd-tree)Coherence-exploiting schemes, such as?sweep and prune?with insertion sort, or tree-tree collisions with front tracking.Hybrid methods involving a combination of various of these schemes, e.g. a coarse AABB tree plus sweep-and-prune with coherence between colliding leaves.Other effects which may be simulated via the methods of soft-body dynamics are:Destructible?materials:?Fracture?of brittle solids,?cutting?of soft bodies, and?tearing?of cloth. The?finite element method?is especially suited to modelling fracture as it includes a realistic model of the distribution of internal stresses in the material, which physically is what determines when fracture occurs, according to?fracture mechanics.Plasticity?(permanent deformation) and?meltingSimulated hair, fur, and feathersSimulated organs for biomedical applicationsSimulation of fluids in the context of computer graphics?would not normally be considered soft-body dynamics, which is usually restricted to mean simulation of materials which have a tendency to retain their shape and form. In contrast, a?fluid?assumes the shape of whatever vessel contains it, as the particles are bound together by relatively weak forces.Rigid body dynamicsIn?physics,?rigid body dynamics?is the study of the?motion?of?rigid bodies. Unlike?particles, which move only in three?degrees of freedom?(translation in three directions), rigid bodies occupy space and have geometrical properties, such as a?centre of mass,?moments of inertia, etc., that characterize motion in six?degrees of freedom?(translation in three directions plus?rotation?in three directions). Rigid bodies are also characterized as being non-deformable, as opposed to?deformable bodies. As such,?rigid body dynamics?is used heavily in analyses and?computer simulations?of physical systems and machinery where rotational motion is important, but?material deformation?does not have a significant effect on the motion of the system.Rigid body linear momentumNewton's Second Law?states that the rate of change of the?linear momentum?of a particle with constant?mass?is equal to the sum of all external?forces?acting on the particle:where?m?is the particle's mass,?v?is the particle's velocity, their product?mv?is the linear momentum, and?fi?is one of the?N?number of forces acting on the particle.Because the mass is constant, this is equivalent toTo generalize, assume a body of finite mass and size is composed of such particles, each with?infinitesimal?mass dm. Each particle has a position vector?r. There exist internal forces, acting between any two particles, and external forces, acting only on the outside of the mass. Since velocity?v?is the?derivative?of position?r, the derivative of velocity dv/dt?is the second derivative of position d2r/dt2, and the linear momentum equation of any given particle isWhen the linear momentum equations for all particles are added together, the internal forces sum to zero according to?Newton's third law, which states that any such force has opposite magnitudes on the two particles. By accounting for all particles, the left side becomes an integral over the entire body, and the second derivative operator can be moved out of the integral, so.Let?M?be the total mass, which is constant, so the left side can be multiplied and divided by?M, so.The expression??is the formula for the position of the?centre of mass. Denoting this by?rcm, the equation reduces toThus, linear momentum equations can be extended to?rigid bodies?by denoting that they describe the motion of the?centre of mass?of the body. This is known as?Euler's first law.Rigid body angular momentumThe most general equation for rotation of a rigid body in three dimensions about an arbitrary origin?O?with axes?x,?y,?z?iswhere the?moment of inertia tensor,?, is given byGiven that?Euler's rotation theorem?states that there is always an?instantaneous axis of rotation, the?angular velocity,?, can be given by a vector over this axiswhere??is a set of mutually?perpendicular?unit vectors?fixed in a?reference frame.Rotating a rigid body is equivalent to rotating a?Poinsot ellipsoid.Angular momentum and torqueSimilarly, the?angular momentum??for a system of particles with linear momenta?pi?and distances?ri?from the rotation axis is definedFor a rigid body rotating with angular velocity?ω?about the rotation axis??(a?unit vector), the velocity vector??may be written as a?vector cross productWhere angular velocity vector??is the shortest vector from the rotation axis to the point mass.Substituting the formula for??into the definition of??yieldsWhere we have introduced the special case that the position vectors of all particles are perpendicular to the rotation axis (e.g.,?a?flywheel):?.The?torque??is defined as the rate of change of the angular momentum?If I is constant (because the inertia tensor is the identity, because we work in the intrinsically frame, or because the torque is driving the rotation around the same axis??so that?I?is not changing) then we may writeWhere α?is called the?angular acceleration?(or?rotational acceleration) about the rotation axis.Notice that if I is not constant in the external reference frame (i.e. the three main axes of the body are different) then we cannot take the I outside the derivate. In these cases we can havetorque-free precession.ApplicationsComputer?physics engines?use rigid body dynamics to increase interactivity and realism in?video games. INDEX \c "2" \z "2057" No index entries found.Use of advanced computer graphics in architectural draughting.AUTOCADAutoCAD?is a?CAD?(Computer Aided Design or Computer Aided Drafting)?software application?for?2D?and?3D?design?and?drafting. It is developed and sold by?Autodesk, Inc.?First released in December 1982, AutoCAD was one of the first CAD programs to run on?personal computers, notably the?IBM PC. At that time, most other CAD programs ran on?mainframe computers?or?mini-computers?which were connected to a graphics?computer terminal?for each user. AutoCad and its vertical products are incompatible with?Bit Defender?security software. Early releases of AutoCAD used primitive entities — lines, poly lines, circles, arcs, and text — to construct more complex objects. Since the mid-1990s, AutoCAD has supported custom objects through its C++?Application Programming Interface?(API). Modern AutoCAD includes a full set of basic?solid modelling?and 3D tools. With the release of AutoCAD 2007 came improved 3D modelling, which meant better navigation when working in 3D. Moreover, it became easier to edit 3D models. The?mental ray?engine?was included in?rendering, it was now possible to do quality renderings. AutoCAD 2010 introduced parametric functionality and mesh modelling.AutoCAD supports a number of APIs for customization and automation. These include?AutoLISP,?Visual LISP,?VBA,?.NET?and Object ARX. Object ARX is a?C++?class library, which was also the base for products extending AutoCAD functionality to specific fields, to create products such as AutoCAD Architecture, AutoCAD Electrical, AutoCAD Civil 3D, or third-party AutoCAD-based applications.AutoCAD and AutoCAD LT are available for?English,?German,?French,?Italian,?Spanish,?Japanese,?Korean,?Chinese Simplified,?Chinese Traditional,?Russian,?Czech,?Polish,?Hungarian,?Brazilian Portuguese,?Danish,?Dutch,?Swedish,?Finnish,?Norwegian, and?Vietnamese. The extent of localization varies from full translation of the product to documentation only. The AutoCAD command set is localized as a part of the software localization.AutoCAD originAutoCAD was derived from a program called Interact, which was written in a proprietary language (SPL) and ran on the Marinchip Systems 9900 computer (Marinchip was owned by Autodesk co-founders?John Walker?and Dan Drake.)When Marinchip Software Partners (later to be renamed Autodesk) was formed, they decided to re-code Interact in C and?PL/1?-- C, because it seemed to be the biggest upcoming language, and PL/1. In the end, the PL/1 version was unsuccessful. The C version was, at the time, one of the most complex programs in that language to date. Autodesk even had to work with the compiler developer (Lattice) to fix certain limitations to get AutoCAD to run. AutoCAD LTAutoCAD LT is a lower cost version of AutoCAD with reduced capabilities first released in November 1993. AutoCAD LT, priced at $495, became the first product in the company's history priced below $1000 to bear the name "AutoCAD". In addition to being sold directly by Autodesk, it can also be purchased at computer stores, unlike the full version of AutoCAD which must be purchased from official Autodesk dealers. Autodesk developed AutoCAD LT so that they would have an entry-level CAD package to compete in the lower price level.As of the 2011 release the AutoCAD LT MSRP has risen to $1200. While there are hundreds of small differences between the full AutoCAD package and AutoCAD LT, currently there are a few recognized major differences in the software's features:3D Capabilities: AutoCAD LT lacks the ability to create, visualize and render 3D models as well as 3D work Licensing: AutoCAD LT cannot be used on multiple machines over a network.Customization: AutoCAD LT does not support customization with LISP, ARX, and VBA.Management and automation capabilities with Sheet Set Manager and Action Recorder.CAD standards management tools.AutoCAD FreestyleBuilt on the AutoCAD platform,?AutoCAD Freestyle?is a simplified, low-cost (US$149) application that makes it easy to create accurate, professional-looking 2D drawings and sketches.Student versionsAutoCAD is licensed at a significant discount over commercial retail pricing to qualifying students and teachers, with a 36-month license available. The student version of AutoCAD is functionally identical to the full commercial version, with one exception: DWG files created or edited by a student version have an internal bit-flag set (the "educational flag"). When such a DWG file is printed by any version of AutoCAD (commercial or student), the output will include a plot stamp / banner on all four sides. Objects created in the Student Version cannot be used for commercial use. These Student Version objects will "infect" a commercial version DWG file if imported. The?Autodesk student community?provides registered students with free access to different Autodesk applications.Vertical programsAutodesk has also developed a few vertical programs, for discipline-specific enhancements.?AutoCAD Architecture?(formerly Architectural Desktop), for example, permits architectural designers to draw 3D objects such as walls, doors and windows, with more intelligent data associated with them, rather than simple objects such as lines and circles. The data can be programmed to represent specific architectural products sold in the construction industry, or extracted into a data file for pricing, materials estimation, and other values related to the objects represented. Additional tools allow designers to generate standard 2D drawings, such as elevations and sections, from a 3D architectural model. Similarly, Civil Design, Civil Design 3D, and Civil Design Professional allow data-specific objects to be used, allowing standard civil engineering calculations to be made and represented easily.?AutoCAD Electrical, AutoCAD Civil 3D, AutoCAD Map 3D,?AutoCAD Mechanical, AutoCAD MEP, AutoCAD P&ID, AutoCAD Plant 3D and AutoCAD Structural detailing are other examples of industry-specific CAD applications built on the AutoCAD platform.AutoCAD ArchitectureAutoCAD Architecture?(abbreviated as ACA) is a version of?Autodesk's flagship product,?AutoCAD, with tools and functions specially suited to?architectural?work.Architectural objects have a relationship to one another and interact with each other intelligently. For example, a window has a relationship to the wall that contains it. If you move or delete the wall, the window reacts accordingly. Objects can be represented in both 2D and 3D.In addition, intelligent architectural objects maintain dynamic links with construction documents and specifications, resulting in more accurate project deliverables. When someone deletes or modifies a door, for example, the door schedule can be automatically updated. Spaces and areas update automatically when certain elements are changed, calculations such as square footage are always up to date.AutoCAD Architecture uses the?DWG?file format but an object enabler?is needed to access, display, and manipulate object data in applications different from AutoCAD Architecture.AutoCAD Architecture was formerly known as AutoCAD Architectural Desktop (often abbreviated ADT) but Autodesk changed its name for the 2008 edition. The change was made to better match the names of Autodesk's other discipline-specific packages, such as?AutoCAD Electrical?and?AutoCAD Mechanical.Autodesk MayaMaya?was originally a next-generation animation product under development at Alias Research, Inc. based on code from a previous Alias product,?Alias Sketch!, a 3D modeler and renderer for the?Macintosh?that lacked animation features. The code was ported to?IRIX?and animation features were added. The codename for this porting project was?Maya.[4]?Walt Disney Feature Animation?collaborated closely with Maya's development during its production of?Dinosaur.[5]?Disney requested that the?User interface?of the application be customizable so that a personalized workflow could be created. This was a particular influence in the open architecture of?Maya, and partly responsible for it's becoming so popular in the industry.After?Silicon Graphics Inc.?acquired both Alias and?Wavefront Technologies, Inc., Wavefront's next-generation technology (then under development) was merged into Maya. SGI's acquisition was a response to?Microsoft Corporation?acquiring?Softimage, Co.. The new wholly-owned subsidiary was named "Alias Wavefront”.In the early days of development, Maya started with?Tcl?as the scripting language, in order to leverage its similarity to a Unix shell language. But after the merger with Wavefront Sophia, the scripting language in Wavefront's?Dynamation, was chosen as the basis of MEL (Maya embedded language). Maya 1.0 was released in February 1998. Alias was successful in expanding its market share, with leading visual effects companies such as?Industrial Light and Magic?and?Tippett Studio?switching from?SoftImage?to?Maya.Following a series of acquisitions, Maya was bought by Autodesk in 2005.?Under the name of the new parent company,?Maya?was renamed?Autodesk Maya. However, the name "Maya" continues to be the dominant name used for the product.AwardsOn February 8, 2008 Duncan Brinsmead,?Jos Stam, Julia Pakalns and?Martin Werner?received an?Academy Award?for Technical Achievement for the design and implementation of the Maya Fluid Effects system.[11][12]OverviewMaya?is an application used to generate 3D assets for use in film, television, game development and architecture. The software was initially released for the IRIX operating system, however this support was discontinued in August 2006 after the release of version 6.5. Maya was available in both "Complete" and "Unlimited" editions until August 2008, when it was turned into a single suite.[13]Users define a virtual workspace (scene) to implement and edit media of a particular project. Scenes can be saved in a variety of formats, the default being?.mb?(Maya Binary). Maya exposes a?node graph architecture. Scene elements are?node-based, each node having its own attributes and customization. As a result, the visual representation of a scene is based entirely on a network of interconnecting nodes, depending on each others information. For the convenience of viewing these networks, there is a?dependency?and a?directed acyclic ponentsSince its consolidation from two distinct packages,?Maya?and later contain all the features of the now defunct?Unlimited?suites.Fluid EffectsA realistic fluid simulator (effective for smoke, fire, clouds and explosions, added in Maya 4.5)Classic ClothCloth simulation to automatically simulate clothing and fabrics moving realistically over an animated character. The Maya Cloth toolset has been upgraded in every version of Maya released after Spider-Man 2. Alias worked with Sony Pictures Imageworks to get Maya Cloth up to scratch for that production, and all those changes have been implemented, although the big studios opted to use third party plugins such as?Syflex?instead of the (relatively) cumbersome Maya Cloth.FurAnimal fur simulation similar to Maya Hair. It can be used to simulate other fur-like objects, such as grass.HairA simulator for realistic-looking human hair implemented using curves and Paint Effects. These are also known as dynamic curves.Maya LiveA set of motion tracking tools for CG matching to clean plate footage.nClothAdded in version 8.5, nCloth is the first implementation of Maya Nucleus, Autodesk's simulation framework. nCloth gives the artist further control of cloth and material simulations.nParticleAdded in version 2009, nParticle is addendum to Maya Nucleus toolset. nParticle is for simulating a wide range of complex 3D effects, including liquids, clouds, smoke, spray, and dust.MatchMoverAdded to Maya 2010, this enables compositing of CGI elements with motion data from video and film positeAdded to Maya 2010, this was earlier sold as?Autodesk Toxik.Camera SequencerAdded after Maya unlimited 2009, Camera Sequencer is used to layout multiple camera shots and manage them in one animation sequence.Maya Embedded LanguageAlongside its more recognized visual workflow,?Maya?is equipped with its very own cross-platform scripting language, fittingly called Maya Embedded Language. MEL, as it is often shortened to, is provided not only for scripting, but also as a means to customize the core functionality of the software, since much of the tools and commands used are written in it. Code can be used to engineer modifications,?plug-ins?or be?injected?into?runtime. Outside these superficial uses of the language, user interaction is recorded in MEL, allowing even inexperienced users to implement?subroutines. Scene information can thus be?dumped, extension?.ma, editable outside?Maya?in any?text editor.System requirementsOperating systemsAutodesk supports the Windows and Mac platforms;?XP SP3?or later respectively. As of?Maya 2011, the software is 64-bit under Mac OS X.[14]?While Autodesk acknowledges that the application is not limited to the aforementioned releases, such as the specific Linux distribution,[15], it does not support them.Autodesk RevitRevit?is a?Building Information Modelling?software for?Microsoft Windows, developed by?Autodesk. It allows the user to design with both parametric?3D modelling?and 2D drafting elements. Building Information Modelling is a?Computer Aided Design?(CAD) paradigm that employs intelligent 3D objects to represent real physical building components such as walls and doors.In addition, Revit's database for a project can contain information about a project at various stages in the building's lifecycle, from concept to construction to decommissioning. This is sometimes called 4D CAD where time is the fourth dimension.Autodesk purchased the Massachusetts-based Revit Technology Corporation for US$133 million in 2002.[1]The latest released version is Revit Architecture/Structure/MEP 2011 (April, 2010)[2]?and the corresponding AutoCAD Revit Suite 2011 products. (AutoCAD Revit Suite combines a seat of AutoCAD with a seat of Revit on a given workstation for a slightly higher price than Revit alone.) On September 29, 2008, Autodesk released 64-bit versions of Revit 2009 products for subscription customers. Both 32-bit and 64-bit versions of Revit 2010 and 2011 products are available without subscription in the standard installation. Revit is localized into multiple languages, including German, French, Italian, Spanish, Czech, Polish, Hungarian and Russian.Revit uses .RVT files for storing BIM models. Typically, a building is made using 3D objects to create walls, floors, roofs, structure, windows, doors and other objects as needed. These parametric objects?— 3D building objects (such as windows or doors) or 2D drafting objects (such as surface patterns)?— are called "families" and are saved in .RFA files, and imported into the RVT database as needed.A Revit model is a single?database?file represented in the various ways which are useful for design work. Such representations can be plans, sections, elevations, legends, and schedules. Because changes to each representation of the database model are made to one central model, changes made in one representation of the model (for example a plan) are propagated to other representations of the model (for example elevations). Thus, Revit drawings and schedules are always fully coordinated in terms of the building objects shown in drawings.When a project database is shared, a central file is created which stores the master copy of the project database on a file server on the office's?LAN. Each user works on a copy of the central file (known as the local file), stored on the user's workstation. Users then save to the central file to update the central file with their changes and to receive changes from other users. Revit checks with the central file whenever a user starts working on an object in the database to see if another user is editing the object. This procedure prevents two users from making the same change simultaneously and prevents conflicts.Multiple disciplines working together on the same project make their own project databases and link in the other consultants' databases for verification. Revit can perform?collision checking, which detects if different components of the building are occupying the same physical space. Revit is one of many BIM-software which supports open XML-based?IFC?standard, developed by?building SMART?organization. This filetype makes it possible for a client or general contractor to require BIM-based workflow from the different discipline consultants of a building project. Because IFC is non-proprietary format it is archivable and compatible with other databases, such as?facility management software.ModellingRevit uses a similar work environment to?Inventor?to create its 3D models, allowing users to?extrude, revolve, trace the path of, or morph shapes drawn on a 3D plane in order to make them into 3D objects, as well as do these actions to already made solid objects to cut or reform them. However, Revit lacks the ability to allow the user to manipulate the object's individual polygons.As simple or primitive as this may seem, an experienced user can create realistic and accurate models of objects, as well as import premade models from other programs. This also ensures that the generative components of an object are retained so they can be parametrically controlled. Revit families can be created with dimensions controlled by parameters (parametric). This allows users to modify the component by changing predefined values such as?height?and?width.Intended useRevit is intended to be a major component in?Building Information Modelling. A main function of Revit is to eliminate redundancies such as having multiple models across industries. Currently, architects, consultants, general contractors, and manufacturers all create their own models and databases from information handed down in a chain of command. BIM intends to replace this approach with a more centralized one. Revit models created in different disciplines (Architectural, Structural, and Mechanical) can be linked and/or combined into one model. This allows a single model and associated database to be kept, ensuring that all parties have the latest information and that there are no errors in translation. Revit also utilizes its rendering engine to remove the interpretation from complex geometries, allowing more intricate designs to be made and understood.Family based contentRevit uses the term 'family' to describe a discrete definition of a part of the building model. There are many Categories of Families, but three main types: System, Component and In-Place Families. Where other programs may use terms such as 'block' or 'insert', Revit uses the term 'Family'.A hierarchical system is used, where a Family tells Revit how to make something, a Type (of a Family) forces certain parameters to be applied, and an Element (or Instance) (of a Type) is the actual part of the building model. For example, a Swing Door may be the name of a Family. It may have Types describing different sizes, and the actual building model will have instances of those types placed in Walls.RenderingWhen a user makes a building, room, model, or any other kind of object in Revit, she or he may use Revit's?rendering?engine to make a very realistic image of what is otherwise a very diagrammatic model. This is accomplished by either using the premade model, wall, floor, etc., tools, or making her or his own models, walls, materials, etc.. The wall- and model- making process is simple enough to pick up in a day or so. Revit 2010 comes with a plethora of premade materials, each of which can be modified to the user's desires. The user can also begin with a "Generic" material, which can be customized to a level of detail not offered by many 3D modeling programs. With this, the user can set the rotation, size, brightness, and intensity of textures, gloss maps (also known as shinemaps), transparency maps, reflection maps, oblique reflection maps, hole maps, and bump maps, as well as leaving the map part out and just using the sliders for any one (or all or none) of the aforementioned features of textures. To the right is an example of what can be accomplished when an experienced user implements all the techniques listed in this section, using only Revit.Autodesk 3ds MaxAutodesk 3ds Max, formerly?3D Studio MAX, is a modeling, animation and rendering package developed by?Autodesk Media and Entertainment. It has modeling capabilities, a flexible?plugin?architecture and can be used on the Microsoft Windows platform. It's frequently used by?video game developers, TV commercial studios and architectural visualization studios. It is also used for movie effects and movie pre-visualization.In addition to its modeling and animation tools, the latest version of 3ds Max also features?shaders?(such as?ambient occlusion?and subsurface scattering),?dynamic simulation,?particle systems,?radiosity,?normal map?creation and rendering,?global illumination, a customizable?user interface, and its own?scripting language.The original 3D Studio product was created for the DOS platform by the Yost Group and published by Autodesk. After 3D Studio Release 4, the product was rewritten for the Windows NT platform, and re-named "3D Studio MAX." This version was also originally created by the Yost Group. It was released by Kinetix, which was at that time Autodesk's division of media and entertainment. Autodesk purchased the product at the second release mark of the 3D Studio MAX version and internalized development entirely over the next two releases. Later, the product name was changed to "3ds max" (all lower case) to better comply with the naming conventions of?Discreet, a Montreal-based software company which Autodesk had purchased. At release 8, the product was again branded with the Autodesk logo, and the name was again changed to "3ds Max" (upper and lower case). At release 2009, the product name changed to "Autodesk 3ds Max".FeaturesMAXScriptMAXScript is a built-in scripting language, and can be used to automate repetitive tasks, combine existing functionality in new ways, develop new tools and user interfaces and much more. Plugin modules can be created entirely in MAXScript.Character StudioCharacter Studio was a plugin which since version 4 of Max is now integrated in 3D Studio Max, helping user to animate virtual characters. The system works using a character rig or "Biped" which is pre-made and allows the user to adjust the rig to fit the character they will be animating. Dedicated curve editors and motion capture data import tools make Character Studio ideal for character animation. "Biped" objects have other useful features that automated the production of?walk cycles?and movement paths, as well as secondary motion.Scene ExplorerScene Explorer, a tool that provides a hierarchical view of scene data and analysis, facilitates working with more complex scenes. Scene Explorer has the ability to sort, filter, and search a scene by any object type or property (including metadata). Added in 3ds Max 2008, it was the first component to facilitate .NET managed code in 3ds Max outside of MAXScript.DWG Import3ds Max supports both import and linking of DWG files. Improved memory management in 3ds Max 2008 enables larger scenes to be imported with multiple objects.Texture Assignment/Editing3ds Max offers operations for creative texture and planar mapping, including tiling, mirroring, decals, angle, rotate, blur, UV stretching, and relaxation; Remove Distortion; Preserve UV; and UV template image export. The texture workflow includes the ability to combine an unlimited number of textures, a material/map browser with support for drag-and-drop assignment, and hierarchies with thumbnails. UV workflow features include Pelt mapping, which defines custom seams and enables users to unfold UVs according to those seams; copy/paste materials, maps and colors; and access to quick mapping types (box, cylindrical, spherical).General Key-framingTwo keying modes — set key and auto key — offer support for different keyframing workflows.Fast and intuitive controls for key-framing — including cut, copy, and paste — let the user create animations with ease. Animation trajectories may be viewed and edited directly in the viewport.Constrained AnimationObjects can be animated along curves with controls for alignment, banking, velocity, smoothness, and looping, and along surfaces with controls for alignment. Weight path-controlled animation between multiple curves, and animate the weight. Objects can be constrained to animate with other objects in many ways — including look at, orientation in different coordinate spaces, and linking at different points in time. These constraints also support animated weighting between more than one target.All resulting constrained animation can be collapsed into standard keyframes for further editing.SkinningEither the Skin or Physique modifier may be used to achieve precise control of skeletal deformation, so the character deforms smoothly as joints are moved, even in the most challenging areas, such as shoulders. Skin deformation can be controlled using direct vertex weights, volumes of vertices defined by envelopes, or both.Capabilities such as weight tables, paintable weights, and saving and loading of weights offer easy editing and proximity-based transfer between models, providing the accuracy and flexibility needed for complicated characters.The rigid bind skinning option is useful for animating low-polygon models or as a diagnostic tool for regular skeleton animation.Additional modifiers, such as Skin Wrap and Skin Morph, can be used to drive meshes with other meshes and make targeted weighting adjustments in tricky areas.Skeletons and?Inverse Kinematics?(IK)Characters can be rigged with custom skeletons using 3ds Max bones, IK solvers, and rigging tools powered by Motion Capture Data.All animation tools — including expressions, scripts, list controllers, and wiring — can be used along with a set of utilities specific to bones to build rigs of any structure and with custom controls, so animators see only the UI necessary to get their characters animated.Four plug-in IK solvers ship with 3ds Max: history-independent solver, history-dependent solver, limb solver, and spline IK solver. These powerful solvers reduce the time it takes to create high-quality character animation. The history-independent solver delivers smooth blending between IK and FK animation and uses preferred angles to give animators more control over the positioning of affected bones.The history-dependent solver can solve within joint limits and is used for machine-like animation. IK limb is a lightweight two-bone solver, optimized for real-time interactivity, ideal for working with a character arm or leg. Spline IK solver provides a flexible animation system with nodes that can be moved anywhere in 3D space. It allows for efficient animation of skeletal chains, such as a character’s spine or tail, and includes easy-to-use twist and roll controls.Integrated Cloth SolverIn addition to reactor’s cloth modifier, 3ds Max software has an integrated cloth-simulation engine that enables the user to turn almost any 3D object into clothing, or build garments from scratch. Collision solving is fast and accurate even in complex simulations.(image.3ds max.jpg)Local simulation lets artists drape cloth in real time to set up an initial clothing state before setting animation keys.Cloth simulations can be used in conjunction with other 3ds Max dynamic forces, such as Space Warps. Multiple independent cloth systems can be animated with their own objects and forces. Cloth deformation data can be cached to the hard drive to allow for non-destructive iterations and to improve playback performance.Integration with Autodesk VaultAutodesk Vault?plug-in, which ships with 3ds Max, consolidates users’ 3ds Max assets in a single location, enabling them to automatically track files and manage work in progress. Users can easily and safely share, find, and reuse 3ds Max (and design) assets in a large-scale production or visualization environment.Modelling techniquesPolygon modellingPolygon modelling is more common with game design than any other modelling technique as the very specific control over individual polygons allows for extreme optimization. Usually, the modeller begins with one of the 3ds max primitives, and using such tools as?bevel?and?extrude, adds detail to and refines the model. Versions 4 and up feature the Editable Polygon object, which simplifies most mesh editing operations, and provides subdivision smoothing at customizable levels.Version 7 introduced the?edit poly?modifier, which allows the use of the tools available in the editable polygon object to be used higher in the modifier stack (i.e., on top of other modifications)NURBS or non-uniform rational B-splineAn alternative to polygons, it gives a smoothed out surface that eliminates the straight edges of a polygon model.?NURBS?is a mathematically exact representation of freeform surfaces like those used for car bodies and ship hulls, which can be exactly reproduced at any resolution whenever needed. With NURBS, a smooth sphere can be created with only one face.The non-uniform property of NURBS brings up an important point. Because they are generated mathematically, NURBS objects have a parameter space in addition to the 3D geometric space in which they are displayed. Specifically, an array of values called knots specifies the extent of influence of each control vertex (CV) on the curve or surface. Knots are invisible in 3D space and you can't manipulate them directly, but occasionally their behaviour affects the visible appearance of the NURBS object. This topic mentions those situations. Parameter space is one-dimensional for curves, which have only a single U dimension topologically, even though they exist geometrically in 3D space. Surfaces have two dimensions in parameter space, called U and V.NURBS curves and surfaces have the important properties of not changing under the standard geometric affine transformations (Transforms), or under perspective projections. The CVs have local control of the object: moving a CV or changing its weight does not affect any part of the object beyond the neighbouring CVs. (You can override this property by using the Soft Selection controls.) Also, the control lattice that connects CVs surrounds the surface. This is known as the convex hull property.Surface tool/Editable patch objectSurface tool?was originally a 3rd party plugin, but Kinetix acquired and included this feature since version 3. The surface tool is for creating common 3ds Max splines, and then applying a modifier called "surface." This modifier makes a surface from every 3 or 4 vertices in a grid. This is often seen as an alternative to "mesh" or "nurbs" modelling, as it enables a user to interpolate curved sections with straight geometry (for example a hole through a box shape). Although the surface tool is a useful way to generate parametrically accurate geometry, it lacks the "surface properties" found in the similar Edit Patch modifier, which enables a user to maintain the original parametric geometry whilst being able to adjust "smoothing groups" between faces.Predefined primitivesThis is a basic method, in which one models something using only boxes, spheres, cones, cylinders and other predefined objects from the list of?Predefined Standard Primitives?or a list of?Predefined Extended Primitives. One may also apply boolean operations, including subtract, cut and connect. For example, one can make two spheres which will work as?blobs?that will connect with each other. These are called?metaballs.Some of the 3ds Max Standard Primitives as they appear in the wireframe view of 3ds Max 9Some of the 3ds Max Extended Primitives as they appear in the wireframe view of 3ds Max 9Predefined Standard Primitives listBox?— box produces a?rectangular prism. An alternative variation of box is available — entitled cube — which proportionally constrains the length, width and height of the box.Cylinder?— cylinder produces a cylinder.Torus?— torus produces a torus — or a ring — with a circular cross section, sometimes referred to as a doughnut.Teapot?— teapot produces the Utah teapot. Since the teapot is a parametric object, the user can choose which parts of the teapot to display after creation. These parts include the body, handle, spout and lid.Cone?— cone produces round cones — either upright or inverted.Sphere?— sphere produces a full sphere, hemisphere, or other portion of a sphere.Tube?— tube can produce both round and prismatic tubes. The tube is similar to the cylinder with a hole in it.Pyramid?— The pyramid primitive has a square or rectangular base and triangular sides.Plane?— The plane object is a special type of flat polygon mesh that can be enlarged by any amount at render time. The user can specify factors to magnify the size or number of segments, or both. Modifiers such as displace can be added to a plane to simulate a hilly terrain.Geosphere?— GeoSphere produces spheres and hemispheres based on three classes of regular polyhedrons.Predefined Extended Primitives listHedra?— produces objects from several families of?polyhedra..ChamferBox — creates a box with beveled or rounded edges.OilTank — creates a cylinder with convex caps.Spindle?— creates a cylinder with conical caps.Gengon — creates an extruded, regular-sided polygon with optionally filleted side edges.Prism?— Creates a three-sided prism with independently segmented sides.Torus knot?— creates a complex or knotted torus by drawing 2D curves in the normal planes around a 3D curve. The 3D curve (called the Base Curve) can be either a circle or a torus knot. It can be converted from a torus knot object to a NURBS surface.ChamferCyl — creates a cylinder with beveled or rounded cap edges.Capsule — creates a cylinder with hemispherical caps.L-Ext — creates an extruded L-shaped object.C-Ext — creates an extruded C-shaped object.Hose — a flexible object, similar to a spring.RenderingScanline renderingThe default rendering method in?3DS Max?is scanline rendering. Several advanced features have been added to the scanliner over the years, such as global illumination, radiosity, andray tracing.Mental ray mental ray?is a production quality renderer developed by?mental images. It is integrated into the later versions of 3ds Max, and is a powerful raytracing renderer with?bucket rendering, a technique that allows distributing the rendering task for a single image between several computers efficiently, using TCP network protocol.RenderManA third party connection tool to RenderMan pipelines is also available for those that need to integrate?Max?into Renderman render farms.V-RayA third-party render engine plug-in for 3D Studio MAX. It is widely used, frequently substituting the standard and mental ray renderers which are included bundled with 3ds Max. V-Ray continues to be compatible with older versions of 3ds Max.Brazil R/SA third-party high-quality photorealistic rendering system created by SplutterFish, LLC capable of fast ray tracing and global illumination.FinalRenderAnother third-party raytracing render engine created by Cebas. Capable of simulating a wide range of real-world physical phenomena.FryrenderA third party photorealistic, physically-based, unbiased and spectral renderer created by RandomControl capable of very high quality and realism.Arion RenderA third party hybrid GPU+CPU interactive, unbiased raytracer created by RandomControl, based on NVIDIA CUDA.Indigo RendererA third-party photorealistic renderer with plugins for 3ds max.Maxwell RenderA third-party photorealistic rendering system created by?Next Limit Technologies?providing robust materials and highly accurate unbiased rendering.BIGrender 3.0Another third-party rendering plugin. Capable of overcoming 3DS rendering memory limitations with rendering huge pictures.Rendering Edges in Google SketchupRendering Mirror surface in 3ds maxRendering Window in 3ds MaxRendered Image in 3ds MaxRendering using artificial lightingLandscaping is a unique feature of Sun based source ................
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